I seriously doubt that except fresh produce in some hellishly hot desert country large scale agriculture using desalinated water makes sense. Much less so if you don't grow some cash crops but have to process it then transport the final product.
There are almost "miracle plants" like Salicornia which can be watered with sea water, but these do not have growth rates of more picky plants like corn or hemp.
If you had a lot of fresh water runoff, you might use that fresh water for drinking rather than desalinating seawater though.
But... If you are using this water for drinking, it's going to come back through the sewage system, and maybe you can dilute the brine with outflows from local sewage treatment plants.
Depending on details, the combined outflow could be more or less salty than the seawater input to the desal plant.
If it's seawater, how are you going to return it to the ocean. You can't dump salt water on land -- it poisons the soil. Even freshwater evaporating in dry climates leads to salinization.
What's that going to cost you in energy inputs (pumping costs)?
Though the thought occurs to me that the Salton Sea in southern California might make a possibly suitable grow region.
Also take into account the much bigger amount that is needed to grow crops and feed livestock; you may be able to use graywater for that, but definitely not saltwater.
Also, water needed by industries and water spoiled by pollution.
We call them “desalination” plants, but the salt doesn’t just disappear. The more fresh water you have them produce, the more salt (brackish water) you need to manage as well.
So even while you may imagine the ocean as a limitless supply of water, there’s only so far you can scale desalination.
IIUC this use the solar power to filter the water, and then it is cultivated in pots or hydroponic or something. So it doesn't matter if the structure is on non arable land or over water.
Being over water simplifies the pipes, but you must be sure that the device floats, this is not so easy, small ships sunk very often and need a lot of maintenance, specially in salty water.
Also, the dome/jellyfish shape is nice, but the light each plant gets is smaller, in a flat surface each plan gets more light. The plants essentially convert sunlight into food, so more sunlight is better.
And most commercial plantation relay in very cheap (or free) water. Any filtration to use salty or polluted water will increase the cost of production.
Desalinating sea water in order to replenish the sweet water reserves we ourselves have degraded with unsustainable practices is pure madness.
What needs to be done instead is to stop interfering with the water cycle [0], let rain water infiltrate the ground, recharge aquifers and restore soil moisture. In order to do that we need to stop the habit of making the ground impermeable (with cement and tar), and stop sending rain water to the sewers to be thrown back to the ocean, and then plant trees. Lots and lots of trees.
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